Automatic transmission



April 2, 1946- c. F. voYTEcH 2,397,634

AUTOMATIC TRANSMISSION Filed OCC. 19, 1945 2 Sheets-Sheet 1 April 2,1946- c. F. voYTl-:CH

AUTOMATIC TRANSMISSION Filed Oct. 19, 1945 2 Sheets-Sheet 2 0,9m w umSw@n Patented Apr. 2, 1946 AUTOMATIC TRANSMISSION Charles F. Voytech,Chicago, Ill., assigner to Borg-Warner Corporation, Chicago, lll., acorporation of Illinois Application October 19, 1943, Serial No. 506,84312 claims. (ci. 'x4-1895) This invention relates to power transmittingdevices and particularly to infinitely variable torque multiplyingdevices combined with gearing. In some of its forms and aspects thisinvention relates particularly to hydrodynamic devices combined withgearing. f

Although the smoothness with which a hydrodynamic torque convertingdevice transmits torque at infinitely varying ratio from a predeterminedmaximum to unity is well known, it is also well known that theeillciency of such a device likewise varies and seldom exceeds 90% underthe most favorable circumstances. This defect has caused designers toincorporate devices which by-pass the torque converter when no torquemultiplication is required and which provide a parallel, more efficientpath to be used with the converter when the latter is multiplyingtorque. Thus an efficient arrangement which has been proposed comprisesa hydraulic torque converter combined with planetary gearing in such amanner that for high torque demand part of input power passes throughthe gearing directly to the driven shaft and the remainder passesthrough the gearing to the converter and thence to the driven shaft,with means for locking up the planetary gearing to provide a 100%mechanical drive between the input and output shafts when no torquemultiplication is required.

Modern automobile engines however are preferably provided with a 3.5ratio rear axle if direct drive is the highest speed obtainable throughthe transmission, or with a ratio of 4.25 if the top speed is anoverdrive. `Thus in the transmission last referred to, a 3.5 axle ratiois required which means that power must be transmitted through theconverter at substantially all times during ordinary city driving andfurthermore that the characteristics of the converter must be such thatit will convert torque over a very large range of speeds both of whichrequirements are diiiicult to meet. To correct this deficiencytherefore, an overdrive ratio should be supplied and the rear axle ratiochanged to 4.25, but this change would of course normally increase thecomplexity of the transmission as well as the number of parts to such anextent that it would render inadvisable the use of the innitely variabletorque converter at all.

It is also known that a reverse drive may be obtained through aconverter without altering the direction of drive of the pump elementthereof, merely by interchanging the functions of the turbine and statoror reaction elements. It has been proposed to incorporate this reversingfeature in a two-path-and-direct-drive arrangement, it being thoughtnecessary however, prior to the present invention, to utilize avsecondary planetary gear set to recombine the two paths of power and tomake possible the interchange of functions.

Considering the foregoing desirable features in a torque converter, andthe desirable features Vprovide a transmission wherein a hydraulictorque converter and a planetary gear set are combined to furnish atwo-path drive of infinitely varying torque ratios under heavy torqueconditions, a mechanical direct drive for medium torque conditions, anda 100% mechanical overdrive for light torque conditions.

Another object of this invention is -to provide a transmissioncomprising a hydraulic torque converter combined with a single planetarygear set with means for securing a reverse driver through thecombination as well as two-path forward drive.

A still further object of this invention is to provide a transmission ofthe torque converter and planetary gear set type which will produce thefunctions and ratios normally required of a transmission in present dayautomobiles and which nevertheless requires no complicated controlmechanism.

A still more specific object of this invention is to provide a simplecontrol mechanism, incorporating both automatic and manual features, forthe combination torque converter and single planetary transmission abovedescribed.

These and other objects of this invention will become apparent from thefollowing detailed description when taken together with the accompanyingdrawings in which:

Fig. 1 is a schematic diagram of the principal elements of thistransmission;

Fig. 2 is a schematic diagram of the hydraulic and mechanical controlsfor the transmission of Fig. 1;

Fig. 3 is a schematic wiring diagram of the electrical controls for thesaid transmission; and

Fig. 4 is a fragmentary development of a clutch taken generally alonglines 4-4 of Fig. 1.

fmounted on a. planet carrier 29.-

to the intermediate position shown in Fig. 1

wherein it is free of both sets of teeth 44 and 45. v

The three positions of sleeve 41 just described correspond to reverse,forward and neutral setset I4 and an automatic clutch I5 whichdlsconnects the transmission from the drive shaft I at speedscorresponding to idling speeds of the prime mover. v

Automatic clutch i5 is mounted on a flywheel I6 having formed thereon astarting gear I1 and drivably supporting a clutch cover |8. Supported inand driven by said cover I8 are weights I9 which are adapted to pivot aton housing |8 to move a clutch pressure plate *2| toward flywheel 6thereby'frictionally driving a clutch driven disc 22. Said driven disc22 may be of any well known -construction, and may incorporate avibration dampening device 23 in the hub section thereof. Clutch coverI8 is also provided with a worm 24 which drives a worm wheel 25 andshaft 92 to supply rotative power to a pump the purposes of which are tobe described hereinafter.

Planetary gear set I4 is comprised of a sun gear 26, a ring gear 21, andone or more planet gears 28 meshing with the ringv and sun gears andSaid carrier 29 is driven directly by clutch driven disc 22.

Hydraulic torque converter I3 is comprised of a vaned pump element 38, afirst stage of turbine vanes 3|, a second stage of turbine vanes 32connected to the first stage 3| by a central web 33, and a vanedreaction or stator element 34. Al direct connection 35 is providedbetween pump element 30 and'sun gear 26 so that the two are constrainedto operate together. Said connection is provided with a brake drum 36with which a brake band 31 is adapted to cooperate to arrest therotation of sun gear 26 and its associated pump element30. The ilrstturbine stage 3| is connected to a drum 38 with which'a brake band 39 isadapted to cooperate to arrest the rotation -of both the first andsecond stages 3| and 32 respectively, of the turbine elements. Reactionelement 34 is connectedthrough a one-way device 40, such for example asthe roller-and-cam mechanism frequently used as a freewheel device, `toa brake drum 4I with which a brake band 42 is adapted to cooperate.One-way device 40,is vso arranged that it will not permit reverserotation of reaction element 34 relative to brake drum 4| but willpermit such reaction element to rov tate freely forwardly with respectto said drum.

Ring gear 21 of planetary gear set I4 is connected to an intermediateshaft 43 which is concentric with shaft and freely rotatable thereon.

' Said intermediate shaft 43 is provided at its right hand end (Fig. l)with external splines 44. Reaction element 34 is also directly connectedto internal splines 45 which are spaced from external splines 44. Shaftis likewise provided with external splines 46 on which is slidablymounted an internally splined sleeve 41, said sleeve being provided withexternal splines 48 at one end thereof which are adapted to mesh withinternal splines 45 in one position of sleeve 41 to provide a directconnection between reaction element 34 and driven shaft II. Sleeve 41 isalso adapted tobe moved to the left (Fig. 1) to engage external splines44 with its internal splines to provide a tings, respectively. A groove49 is provided in sleeve 41 to receive a shift fork 55 (Fig. 2), saidshift fork being pivoted in a lever 5| mounted on a shaft 52 and adaptedto be operated by an external lever 53, connected by a rod 54 to a lever55 at the steering column. Said lever 55 is directly connected to a rod56 which in turn is operated by a hand lever 51 positioned beneath thesteering wheel (not shown) l of the vehicle.

Second turbine stage 3| is also connected through a one-way clutch 58 tointermediate shaft 43, the one-way clutch being so arranged thatintermediate shaft 43 may rotate faster than turbine 3| but thel lattermay not rotate faster than the intermediate shaft.

A clutch 59 is provided for connecting carrier 29 to ring gear 21 tolock up the gear setl in direct drive, which also in effect, connectsdrive shaft I0 with 4driven shaft |I. Said clutch 59 is comprised of aset of clutch teeth 60 mounted on carrier 29, and a cooperating toothedannulus 6| splined at 62 to a cylinder 63 rotatable with driven shaftBoth sets of teeth have double chamfers y as shown in Fig. 4. Anabutment 64 is provided at the end of cylinder 63 and a spring 65 iscompressed between said abutment and the teeth 6| so as to tend tomaintain clutch 59 in a disengaged position. An annular opening 66 is.provided in a cylinder 63 in which is disposed an tion between shaftsIl) and II, the connection is dependent upon the operation of automaticclutch I5 so that should flywheel I6 be rotated at a speed less than thecut-in speed of clutch I5, clutch 59 would be ineffectual to connectdriven shaft II with drive shaft I0.

In order to provide a connection between drive shaft I0 and driven shaftwhen clutch |5 is disengaged, a second positive clutch 1| is provided.This clutch is comprised of a set of teeth 12 on drive shaft I0, acooperating set of ratchet teeth 13 on a slidable clutch-member 14 whichis'splined at 15 to driven shaft and is integral with an annular piston16 concentrically mounted with respect to shaft Said shaft is formedwith an annular opening 11 to receive said piston 16, opening 11 beingin communication ,with a conduit 18 which connects said openingmatically engage and provide a positive connection between drive shaftA|| and drive shaft I8.

The operation of the transmission thus far described is as follows:

Assuming that the transmission is tobe used in an automobile and thatthe automobile is standing still with the engine dead, that is, withdrive shaft I0 stationary, automatic 'clutch I5 is disengaged and clutch1| is engaged by spring 80 thus establishing a direct connection betweendriven shaft and drive shaft I0. Under these conditions should theengine starter fail to oper- `clutch i 5 to carrier 29.

ate, the engine may nevertheless be started by pushing the car sinceclutch 1I, provides the n ecessary connection between shaft I,I anddrive shaft I0. After the engine has been started and is idling, shiftsleeve 41 may be made to assume either one of its three positions. Itshould be noted that said sleeve may be positioned in neutral while theengine is being started by pushing the car since theposition of sleeve41 has no bearing whatsoever upon the operation of clutch 1l. Assuming,however, that sleeve 41 is in the neutral position shown, the rotationof shaft I at engine idling speed will also rotate flywheel I6, clutchcover I8 and the pump drive gears 24, 25 thereby providing fluid underpressure which is conducted through conduits 19 and l18 to opening 11 todisengage teeth 13 from teeth 12 against the action of spring 80. Thusclutch 1I is disengaged when the engine is idling and remains disengaged-as long as fluid pressure is available in conduit 18.

To move the car in forward direction, manual shift lever 51 is rotatedclockwise as viewed in Fig. 2, thereby shifting sleeve 41 to the left asshown in Fig. 1 through the intermediary of the elements 50 to 51inclusive. This connects intermediate shaft 43 to driven shaft II. It iscontemplated that clutch 59 is disengaged under starting conditions. Itis also contemplated that brake band 42 will be tightened upon drum 4Iand brake bands 31 and 39 will be disengaged subsequent to the initialengagement of teeth 44 on intermediate shaft 43 with the internalsplines on sleeve 41 but before the complete engagement of these teethwith one another. The means by which these operations are accomplishedwill be described hereinafter. With drive shaft IIJ rotating aboveidling speed, clutch I5 will engage automatically by the movement ofweights I9 outward and the drive will be transmitted from Since ringgear 21 is connected to intermediate shaft 43 and said shaft 43 isdirectly connected to driven shaft II, the load of the vehicIe willresist the turning of ring 21 and hence said ring gear 21 will functionas a reaction element, thereby causing sun gear 26 to rotate in the samedirection as carrier 29 but at an overspeed with respect thereto. Sungear 26 being directly connected to pump element 30 of the torqueconverter I 3, said pump element will then energize the fluid in theconverter, the energized fluid then impinging successively upon firstturbine stage 3|, reaction element 34 and second turbine stage 32.Reaction element 34, however, is held against rotation by means ofone-way coupling device 40 and the previously tightened brake band 42and hence the energy of the fluid will be absorbed in turning turbineelements 3| and 32 in the same direction as pump element 30. The turningwill be accompanied by increased torque because of the action ofstationary reaction element 34, and this turning effort will betransmitted through one-way clutch 58 to intermediate shaft 43 where itjoins the turning effort impressed upon ring gear 21 by carrier 29 andplanet pinions 28. Thus a two-path drive is effected between drive shaftIlland driven shaft I I, one of the drives being purely mechanicalthrough carrier 29, pinion 28, ring gear 21 and intermediate shaft 43,and the remainder being hydraulic through the converter as justdescribed. As driven shaft II gathers speed the torque ratio becomescloser to unity and torque converter I3 ceases to convert torque. Atthis stage the reaction on reaction element 34 changes its direction sothat it is in a forward direction rather than reverse and hence it willbegin to rotate because it is liberated by the freewheel brake 40,despite the fact that brake band 42 may still be tightened about brakedrum 4I.

Under direct drive conditions through the turbine I3, however, there isstill a considerable loss in efliciency and accordingly clutch 59 may beoperated by the controls hereinafter to be described to connect carrier29 to driven shaft II. To operate clutch 59 fluid is introduced intoannular opening 86 which urges piston 61 against toothed annulus 6I. Thechamfered ends of the teeth resist engagement until substantialsynchronism is effected and hence the net result of the admission offluid under pressure into opening 66 is to compress spring 88. Uponattaining synchronism, as for example by the operator slowing down theengine, spring 68 will snap the teeth of annulus 6I into engagement withclutch eth B0 and provide a one hundred per cent mechanical direct drivebetween carrier 29 and driven shaft II which, as previously stated, isthe equivalent of a direct drive between drive shaft I0 and driven shaftII.

' It is contemplated that this transmission will be used with anautomobile having a rear .axle ratio of approximately 4.25 which hasbeen standard in automobiles for many years- At, say 30 to 60 miles anhour in direct drive with a 4.25 axle the engine may be turning overfaster than is necessary for the power delivered and hence an overdriveis desirable. The overdrive is provided inthe present transmission asfollows:

Without disturbing the setting of sleeve 41 or brake band 42, fluidpressure is removed from opening 66 so as to create an unbalancedcondition tending to disengage clutch 59, and brake 31 is applied tobrake drum 36 to arrest the rotation of sun gear 26. In the transitionfrom direct drive to overdrive `the direction of the torque load onteeth GI will reverse and since said teeth 6I are already biased todisengaged position, as soon as the torque load has reached zero valueclutch 59 will be disengaged. With sun gear 26 stationary and carrier 29driving, ring gear 21 will be driven at an overspeed with respect tocarrier 29 and will therefore drive intermediate shaft 43 and drivenshaft II at an overdrive with respect to drive shaft I0. The arrestingof the rotation of pump element 30 also tends to arrest the rotation ofthe remainder of the elements 3|, 32 and 34 of the converter. Thishowever creates no difficulty since one-way clutch 58 is designed topermit intermediate shaft 43 to rotate ahead of turbine stage 3l andreaction element 34 is expressly designed to be statzonary.

Reverse is obtained by releasing brakes 31 and 42, tightening brake band39 upon drum 38 engaging clutch 59 so as to connect carrier 29 to ringgear 21 and thereby lock up planetary gear set I4, and by shiftingsleeve 41 to the right as shown in Fig. 1 to engage splines 48 withsplines 45. Thus a direct drive is provided through planetary gear setI4 to pump element 30, turbine elements 3l and 32 are held againstrotation and reaction element 34 is connected directly to the drivenshaft I I. Under these conditions the functions of the turbine andreaction elements will be reversed and the reaction element will tend torotate backwardly, thereby driving driven shaft II backward with it.Here again one-way clutch 58 breaks the drive between turbine elements3|, 32 and intermediate shaft 43 thus permitting the latter to rotatewhile the former do not. Since the reverse drive is transmitted througha fluid. the transmission may be shifted into reverse when going down avery steep incline, and by regulating the speed of the engine a powerfulbraking action may be obtained which is more effective than coastingagainst the engine or coasting in gear.

Referring now to Fig. 2 for a description of the hydraulic controls, itis contemplated that brake bands 31, 39 and 42 will be controlled byhydraulic pressure, brake bands 99 and 42 (corresponding to reverse andforward speed respectively) being applied by hydraulic pressure andreleased by spring pressure, and brake band 31 (corresponding to theoverdrive control) being normally applied by spring pressure andreleased by hydraulic pressure. The details of the brakes are not shownsince such details may be readily supplied by one skilled in this art.Thus brake band 31 is released by a piston 8| which is controlled by avalve 82, brake band 38 is tightened or applied to brake drum 38 bypiston 89 which is controlled by a valve 99, and brake band 42 isapplied by a piston 85 which is controlled by a valve 88. Since brakes39 and 42 are to be operated in conjunction with the operation of shiftsleeve 41 their corresponding valves are so p0- sitioned as to beoperated by lever 53. In order to facilitate the engagement of the teethof sleeve 41 with teeth 45 or 44 it is contemplated that brakes 39 and42 will not be applied until after an initial engagement of the teeth onsleeve 41 with teeth 44 or 45. Thus valve 84 is provided with a pin 81which is contacted by lever 53 substantially at the end of its movementtoward reverse position and likewise valve 88 is provided with a pin 88which ls contacted near the end of the movement of lever 53 to itsforward position.

Clutch 59 is controlled by a valve B9 under certain conditions and byvalves 99 and 84 under other conditions as will be hereinafterexplained.

The hydraulic circuits for the various conditions in the transmission ofFig. l are as follows: I

Fluid is drawn from a sump through a conduit 90 by a gear type pump 9|which is driven by the shaft 92. The uid is then pumped under a pressuredetermined by a pressure control valve l i4 into a conduit 93 having abranch 19 leading to clutch 1| and to the converter. It then passesthrough valve 82 into a conduit 91 having a branch 94 leading to valve89, a branch 95 leading to valve 84 and a branch 96 leading to valve 98.Overdrive valve 82 is controlled by means of a solenoid 98, and directdrive valve 89 is controlled by another solenoid 99. Referring to Fig.3, solenoids 98 and 99 are connected in parallel with respect to oneanother and in series with respect to an electric governor switch |00which is prefer` ably driven bydriven shaft Il so as to be responsive tovehicle speed. Said governor switch |00 may be set to engage at anypredetermined speed in the range between 15 and 20 miles per hour.Direct drive solenoid 99 is also in series with a normally closed switch0| which is adapted to be shunted by one arm |02 of a double pole singlethrow switch |03 preferably mounted at the end of lever 51. The otherarm |04 of switch |03 is in series with solenoid 98, both switches I 0|and |03 being in series with a battery |05 and an ignition switch |06. Abranch wire |01 supplies energy to the ignition circuit. Switch |0| hasa pin |08 which is. adapted to be contacted by an accelerator pedal |09prior to the latter reaching full open throttle position. This priorposition is shown in dotted lines at I09a and full open throttleposition is shown at |09b. The purpose of this arrangement is to permita deceleration ofthe engine while switch |0| is open so as to break thecircuit to solenoid 99 and at the same time remove torque from the teetho clutch 59.

' When shift sleeve 41 is in neutral position lever 53 will assume theposition shown in Fig. 2 and hence conduits and 98 will be cut off frompistons 83 and 85 and the fluid then behind these pistons will be ventedthrough conduits ||0 and Ill respectively. Assuming that ignition switch|08 is closed and that the engine is turning over at idling speed itwill be observed that fluid under pressure is conducted through valve 82behind overdrive brake piston 8l to release brake band 351. To shiftsleeve 41 to forward position, lever 51 is moved clockwise as shown inFig. 2 thereby causing lever 53 to move counterclockwise until teeth 44and the internal splines on sleeve 41 are in mesh. In completing theshift, lever 53 contacts and then moves pin 88 causing valve 88 to bemoved to the right, thereby closing od ventvopening and opening pressureconduit 99 to piston 85. This causes the forward brake 42 to be applied.After the vehicle moves f forward and the cut-in speed of governor |00is reached, the circuit is completed through solenoid 99 and switches|04 and |05. This energizes solenoid 99 and causes it to move valve 89downward, thereby closing off the vent opening through conduit i2, valve84 and vent opening |I0, and opening the pressure line 94 to the conduit10 and clutch 59. Said clutch 59 will not engage until -the acceleratorpedal |09 has been raised to relieve the torque as previously described.Assuming however that accelerator pedal |09 has been so manipulated andclutch 59 is engaged, the transmission will be in direct drive as longas both switches |00 and |0| are closed. Should a sudden emergencyrequiring increased torque arise, however, accelerator pedal 09 isdepressed to wide open throttle position and then raised slightly to apoint just short of closing switch |0| thereby deenergizing solenoid 99and allowing valve 89 to close off conduit 94 and reopen vent conduit 2to remove the pressure from behind annular piston 61. The reversal oftorque which accompanied the slight release of accelerator pedal '|09willpermit release spring 6'5 to disengage clutch 59 and thetransmission will then be in its two-path, high torque condition. Thiscondition may obtain as long as accelerator pedal |09 remainssulhciently depressed to keep switch |0| open. To reestablish directdrive .the

accelerator pedal is simply raised to close switch |0| and also to againreverse the direction of torque, whereupon clutch 59 will be reengaged.

Assuming that the transmission is conditioned for direct drive operationand the operator wishes to go into overdrive, he merely operates switch|03 to close the switch arms |02 and |04 thereby rendering inoperativethe downshiftlng switch |01 and also energizing solenoid 98. Withsolenoid 98 energized, valve 82 is pulled up to close oil pressureconduit 93 and open brake piston 8| to a vent opening ||3. Sinceoverdrive brake band 31 is released by fluid pressure and engaged byspring pressure the venting of the pressure behind piston 8| will resultin the application of brake band 31 to brake drum 38 thereby arrestingthe rotation of sun gear 26. The movement of valve 82 upward in responseto ,energization of solenoid 98 dumps all fluid pressure in the systemexcept that in conduits 19 and 93 and hence also removes the fluidpressure from behind piston B1 of clutch 89 despite the fact thatsolenoid 99 is still energized. Since the shift.

from direct drive to overdrive is accompanied by a torque reversal withreference to clutch teeth 60 and toothed annulus 6I of direct driveclutch 59, the mere application of overdrive brake 31 preceded by theventing of the pressure behind drive clutch piston 61 will effect therelease of the direct drive and a shift into overdrive. While inoverdrive, manipulation of kickdown switch IUI has no effect whatsoeverupon the system. To change back to direct drive, as for example, to passanother vehicle, the operator opens switch |03 to deenergize solenoid98. This restores pressure behind pistons 61 and 8l thereby releasingthe overdrive brake, effecting a reversal of torque with respect toclutch teeth 80 and il and reengaging said teeth upon their attainingsubstantial synchronism.

To establish reverse drive, manual shift lever 51 is movedcounterclockwise as viewed in Fig, 2 thereby effecting a clockwisemovement of lever 53 and its associated mechanism to shift sleeve 41 soas to engage teeth 48 with teeth 45, After a partial engagement of saidteeth, pin 81 of valve 84 is contacted by lever 53 and the completion ofthe shift into reverse moves valve 84 to close off vent conduit H andopen pressure conduit 95 to piston B3. Through conduit II2 the pressureis also transmitted to valve 89 and conduit y "through planetary gearset ll and also applies reverse brake band 39 to brake drum 38, theforward brake 42 and overdrive brake 31 being disengaged. Thetransmission is now in condition l for reverse operation.

If desired, the abovedescribed transmission may be operated with theoverdrive switch |03 in closed position at all times except when adownshift is required. Direct drive would thus be omitted in the upwardshift and would be used only in emergencies.

It is understood that the foregoing description is merely illustrativeof a preferred embodiment of the invention. The scope of the invention,therefore, is not to be limited to the foregoing description but is tobe determined by the appended claims.

I claim:

1. In a power transmitting mechanism, drive and driven shafts, a powerdividing differential adapted to be connected to the drive shaft, meansfor transmitting a portion of the divided power from the differential tothe driven shaft, a reversible infinitely variable torque multiplyingdevice having input, forward and reverse connections, means coupling theinput connection to the differential, and selective means forestablishing forward or reverse drive between the driving and drivenshafts including a one-way clutch for coupling the forward connection tothe driven shaft, means for coupling the reverse connection to thedriven shaft, and means for locking up the differential when the reverseconnection is coupled to the driven shaft.

2. In a power transmitting mechanism, drive and driven shafts, a powerdividing differential, a reversible infinitely variable torquemultiplying device having input, forward and reverse connections, andcoupling means for selectively establishing forward or reverse drivethrough the mechanism, said coupling means including means forconnecting the differential to the drive shaft and to the inputconnection for both forward and reverse drives, means for connecting thedifferential and output connections to the driven shaft for forwarddrive, and means for locking up the differential and connecting thereverse connection to the driven shaft for reverse drive.

3. A power transmitting mechanism as described in claim 2, the couplingbetween the forward connection and driven shaft being effective onlywhen power istransmitted by the said forward connection, and means forestablishing a drive solely through the differential.

4. A power transmitting mechanism as described in claim 2, the couplingbetween the forward connection and driven shaft being effective onlywhen power is transmitted through the said forward connection, and meansfor establishing an overdrive through the differential, said infinitelyvariable device being inoperative when the overdrive is established.

5. A power transmitting mechanism comprising Vdrive and driven shafts, apower dividing differential, a hydraulic infinitely variabletorquemultiplying device having pump, turbine and reaction elements, andcoupling means for selectively establishing forward or reverse drivethrough the mechanism, said coupling means including means forconnecting the differential to the drive shaft and to the pump elementfor both forward and reverse drives, means for connecting thedifferential and turbine elements to the driven shaft for forward drive,and means for locking up the differential and interchanging thefunctions oi the turbine and reaction elements for reverse drive, suchthat the reaction element is connected to the driven shaft in place ofthe turbine element and the turbine element acts as a reaction element.

6. In a power transmitting mechanism, drive and driven shafts, avariable speed differential.

an infinitely variable torque multiplying device havingninput and outputconnections, means independent of said differential and device forconnecting the shafts for direct drive, means for obtaining overdrivethrough `the differential, said differential being connectible to thedrive and driven shafts when overdrive is established therein, means fortransmitting part of the power from the drive shaft through thedifferential to the driven shaft and the remainder of the powercomprising sun, ring, planet gears and a planet gear carrier, ahydraulic torque converter comprising pump, turbine and reactionelements, means connecting the sun gear directly to the pump element,means connecting the carrier directly to the drive shaft, anintermediate shaft, means directly connecting the ring gear to theintermediate shaft, one-way means connecting the turbine element to theintermediate shaft,

selective means for arresting the rotation 'of either'the turbineelement or the reaction element, clutch means for connecting the driveshaft to the intermediate shaft. and selective means for connectingeither the intermediate shaft or the reaction element to the drivenshaft, whereby to provide a forward drive through the mechanism when thereaction means is arrested and the intermediate shaft is connected tothe l driven shaft, or a reverse drive when the turbine element isarrested, the drive and intermediate shafts are connected and thereaction element is connected to the driven shaft.

8. .A power transmitting mechanism as described in claim 7, and brakemeans for the sun gear to establish an overdrive through the planetarygear set when the selective means is conditioned for forward drive.

9. A power transmitting device including drive and driven shafts and avariable speed planetary gear mechanism comprising drive, driven andreaction elements, a clutch for connecting two elements of the planetarygear mechanism together for 'direct drive, a friction brake operableupon the third element for producing an overdrive, fluid means forengaging the clutch, fluid means for disengaging the brake, a valve forcontrolling the fluid means for the clutch, a valve for controlling thefluid means for the brake, said valves being interconnected such thatboth said uid means are rendered inoperative when the brake is engaged,manually operated control means for each of said valves, the manualcontrol means for the clutch valve being rendered ineffectual when thecontrol means for the brake has been operated, and speed responsivecontrol means for both valves, said speed responsive control means beingin series with the manual control means.

10. A power transmitting mechanism compris..

`a,sa7,os4 l A action element, and two stages of turbine ,ele-- ments,one stage being disposed on either side of the reaction element and bothstages being connected together, and coupling means for selectivelyestablishing forward and reverse drives through the mechanism, saidcoupling means including means for connecting the diiferential to thedrive .structure and to the pump element for both forward and reversedrives, means for connecting the differential and one stage of theturbine element to the driven structure and means for holding thereaction element for forward drive, and means for holding the otherstage of the turbine element and connecting the reaction element to thedriven structure for reverse drive.

1l. A power transmitting device including drive and driven structuresand a variable speed planetary gear mechanism comprising drive, drivenand reaction elements, a clutch for connecting two elements oftheplanetary gear mechanism together for direct drive, a friction brakeoperable upon one element for producing an overdrive, fluid means forengaging the clutch, iiuid means for disengaging the brake, a valvecontrolling the .n fluid means for the clutch, a valve for controllingthe fluid means for the brake, said valves being interconnected suchthat both said fluid means are rendered inoperative when the brake isen,- gaged, a solenoid for each of said valves, a manually controlledswitch in series with each sole noid, a speed responsive switch, and asource of electrical energy, said solenoids and` solenoid switches beingin parallel with one another and in series with the speed responsiveswitch and source lof electrical energy,

12. A power transmitting device as described in claim 11, a switch inshunt with the direct drive solenoid switch and means for closing saidswitch when the overdrive solenoid switch is ing drive and drivenstructures, a power dividing closed.

diiferential, a hydraulic infinitely variable torque multiplying 'devicehaving a. -pump element, a re- CHARLES F. VOYTECH.

